Condensed Matter Seminar: Maxwell's demon at the nuclear pore: the end of an enigma?

The living cell separates its biochemistry into spatial compartments, the most prominent of which is the nucleus. Protein transport into and out of the nucleus takes place through large aqueous channels in the membrane envelope, the nuclear pores. The transport process is chemically specific and selective so that some proteins accumulate while others are depleted from the nuclear volume. Very simple experiments reveal the basic functions and minimal sets of kinetic equations provide quantitative estimates of the key parameters. At the same time, demixing a solution is a formidable task thermodynamically. We find a fundamental connection between directionality of transport and coupling to an irreversible dissipation of energy. The basic insights may guide the design of synthetic molecular pumps with no moving parts.